Manipulating diverse degrees of freedom in MnTe: Pathways toward enhanced thermoelectric performance

Manganese telluride (MnTe) is a promising mid- to high-temperature thermoelectric system, featuring strong coupling among charge, heat, and spin transport. Its antiferromagnetic order, persistent magnetic excitations, Mn 3d–Te 5p hybridization, structural polymorphism, and rich defect chemistry provide multiple degrees of freedom for tailoring thermoelectric properties. This Review offers a comprehensive overview of MnTe-based thermoelectrics from five interconnected perspectives: spin, charge, orbital, lattice, and phase. We discuss how spin entropy and magnon-related transport, charge carrier characters, band and orbital engineering, multiscale phonon scattering, and impurities can be individually and cooperatively manipulated to enhance thermoelectric performance. Through such multidimensional materials engineering, the peak thermoelectric figure of merit has increased from below unity in pristine MnTe to above 1.6 in optimized compositions. We further examine recent advances and remaining challenges in device development, including performance integration, stability, and practical implementation. Our Review highlights the essence of coordinated control over multiple degrees of freedom and advocates the materials-to-device design strategy for advancing MnTe-based thermoelectrics toward broader energy-conversion applications.